1. Field of Invention
This invention relates to a device and a process for machine diagnostics, by means of a vibration sensor vibration signals on the machine being detected and then being digitally processed.
2. Description of Related Art
In typical applications in machine diagnostics and maintenance, both signal portions in the high and also in the low frequency range must be examined. Since for the same measured quantity (acceleration, velocity, path), different frequency ranges with very different amplitudes occur, the signal is conventionally divided first into different frequency ranges and filtered accordingly, and then, amplified such that the signal of the respective frequency range triggers the analog-digital converter (ADC) as optimally as possible. Signal detection itself can take place either in parallel with several signal paths and ADCs or serially in succession by switching different analog channels to an individual ADC.
One possibility for reducing the number of required ADCs with a uniform measurement time is the use of a higher resolution ADC. This approach is described, for example, in U.S. Pat. No. 5,633,811 where a sigma-delta ADC is used for digitization. Furthermore, U.S. Pat. No. 5,633,811 also gives an example for a slow and a fast ADC being able to be switched in parallel in order to provide for optimized digitization into different frequency ranges. Other examples for use of sigma-delta ADCs for vibration analysis of machines can be found in U.S. Pat. No. 6,507,790 B1 or German Patent Application DE 10 2007 042 678 A1 corresponds to U.S. Pat. No. 7,424,403 B2.
The disadvantage in the use of a high resolution ADC is that the amount of data formed according to the high ADC resolution is very large, and thus, makes further processing of the digitized signal more difficult.